Art of burning pulverized coal



April 2, 1929. J..VAN BRUNT ART OF BURNING PULVERIZED COAL Filed Oct.1924 INVENTOR wlfilu ATTORNEYS Patented Apr. 2, 1929.

UNITED STATES PATENT OFFICE.

JOHN VAN BRUNEI, OF FLUSHING, NEW YORK, ASSIGNOB J30 COMBUSTIONENGINEER- ING CORPORATION, A CORPORATION OF NEW YORK,

am or" BURNING runvnarznn COAL.

Application filed October 3, 1924. Serial No. 741,861.

In the art of burning pulverized coal, it

is a common practice to provide a storage bin or reservoir from whichthe fuel is fed by a feeder means to a pipe leading to the fur- 5 naces,the pipe subdividing into branches,

each of which leads to one or more burners.

It is also a practice in this art, in the so-called direct firingsystem, to lead a feed pipe from a pulverizer to the furnace or furnacesto be fed whereby, such pipe, where more thanone burner is employed,dividing into branches each supplying one or more burners.

The fuel is carried along through the pipe by ablast of what is termedcarrying? air,

the fuel particles being carried in suspension in such air.

It is well known in this art that a stream of pulverized coal and air ina pipe is not of uniform cross-sectional density, as is the case with avapor or gas flowin through a pipe. With pulverized coal flowing throughor down a pipe, there is a point of maximum density or maximum rate offlow, which point does not always remain constant but may move slowlyover a portion of the cross-sectional area.

Hence, when the fuel stream and its carrying air are divided in thebranches of the feed pipe or by partitions along the diameter of thepipe, the branches will not receive the same amount of coal, more coalgoing to one or more of the branches, depending upon the then particularlocation of the point of maximum density. Thus, the rate of feed of coalthrough the branches or compartments is "not the same nor will theproportion remain the same, because of the variable factor incident tothe shifting of the region of maximum density.

This difficulty might be overcome by providing a separate feeder foreach pipe, but the impracticability of this will be apparent for examplewhen it is considered that one furnace may have anywhere from one tohalf a dozen or more burners, all of which can be readily supplied fromone feeder. The cost of providing individual feeders would beprohibitive.

It'is uite important that there should be uniformity of feed and,therefore, it is the object of my invention to provide a simple meanswhereby this uniformity of feed can be obtained, without the greatexpensewhich would be involved in providing individual feeders.

ditioned in accordance with my invention;

How the foregoing, together with such other objects as may hereinafterappear, or are incident to my invention, may be obtained, is illustratedin the accompanying drawings wherein:

Fig. 1 is a vertical section, taken on the line 1--1 of Fig. 8, througha feed pipe which, for purposes of illustration, has a number ofdivisions each of which supply a burner, such pipe having myimprovements applied thereto;

Fig. 2 is a section taken on the line 2-2 of Fig. 1, illustrating theeneral condition of the material in the pipe efore it is recon- Figs. 3to 7 inclusive are cross-sections through the pipe taken at successivepoints, illustrating the manner in which the conditioning is broughtabout;

Fig. 8 is a cross section on the line 8-8 of Fig. 1; and Figs. 9 and 10illustrate modifications of the invention.

Referring now to Fig. 1, the reference numeral 7 designates the feedpipe (in this instance a vertical length of the feed pipe), terminatingat its lower end in a plurality of (four) branch pipes 8 of smallerdiameter. The reference numeral 9 designates a spiral or helical ribbonof sheet metal or the like, having feet 10 at its extremities forpositioning of the helix inthe pipe. The diameter of the helix or'spiralis substantially less than the interior diameter of the pipe. There maybe preferably two of such helixes.

Now referring to Fig. 2, this is a cross section through the pipe inadvance of the helix or conditioning element. The dots indicate thepulverized fuel carried in suspension in the blast of air, the darkspots 11 and 12 indicating zones of greater density. The mix ture ofcoal and air flows with considerable velocity and where it strikes orenters the helix, it is swirled about violently and deflected outward,or more properly speaking the mixture has imparted to it a whirlingmotion, bringing into play the action of centrifugal force which tendsto drive the fuel articles to the periphery. The location 0 the zone orzones of greater density is thus shifted outward as shown in Fig. 3. Asthe mixture continues to flow along the helix, this action is continuedwith the result that the denser portions begin to flatten out along theinner periphery of the pi e, i. e. in the space between the helix an thepipe. Eventually practically all of the coal particles are evenlydistributed as indicated in Fig. 7, the path of the particles being in aspiral. Immediately after leaving the helix the fuel enters the fourcompartments formed by the dividing plates 13. By virtue of the spiralflow of the fuel, the same amount of fuel and also of air will entereach compartment. Air will enter in the compartments, both with the coaland from the core or central region of the pipe, and since the coal andair will strike the division plates and since these compartments vary incross-section from a segment of a circle to a circle, the coal and airwill be agitated and mingled in each branch pipe, so as to bring theparticles into the desired state of-suspension in the air.

In Figs. 9 and 10 I have respectively shown a pipe dividing into threebranches and into two branches.

It will also be apparent that the conditioner may be useful in otherapplications, as for example where it is desired to convey pulverizedcoal over a substantial distance. In such cases it might be desirable torecondition the mixture at intervals so as to secure proper andeffective delivery at the discharge end of the conveyor pipe.

Where two helixes are employed, I prefer to set the second at right anles to the setting of the first, as shown in the rawing, i. e., thefirst has a lead on the second. The twist of the two helixes is thesame.

I claim:

1. Means for delivering finely divided fuel in suspension in a gascomprising a branched conduit having a helix therein in advance of thebranches, the diameter of the helix being substantially less than theinterior diameter of the conduit and means on said helix to position itcoaxially with the conduit, whereby a uniform distribution of fuel tothe branches is secured.

2. Means for delivering finely divided fuel in suspension in a gascomprising a branched conduit having a helix therein in advance of thebranches, the diameter of the helix being substantially less than theinterior diameter of the conduit and means positioning said helixcoaxially with the conduit, whereby a uniform distribution of fuel tothe branches is secured- In testimony whereof, I have hereunto signed myname.

JOHN VAN BRUNT.

